Novel transition between different configurations of planartransmission lines

New designs of coplanar waveguide (CPW)-microstrip, CPW-stripline, conductor backed CPW (CBCPW)-microstrip, and CBCPW-stripline transitions are presented. Simulation using the high frequency structures simulator (HFSS) shows that the return loss of the CPW-microstrip transition is less than -25 dB up to 11 GHz. Similarly is the CPW-stripline transition. In the case of two back to back CBCPW-stripline transitions, the return loss is less than -22 dB up to 9 GHz. Experimentally, the S ₁₁ of two back to back CBCPW-microstrip transitions on an alumina substrate is less than -15 dB up to 25 GHz     

Computer-aided design of microstrip filters by iterated analysis

An iterative method for the design of microstrip low-pass elliptic function filters is described. The method, which is a direct extension of the work of H.J. Orchard (IEEE Trans. Circuit Syst., vol.CAS-32, no.11, p.1089-96, 1985), determines the microstrip line parameters that produce the same locations of the frequencies of transmission zeros and reflection zeros of an equivalent lumped-element prototype. Effects of the discontinuities at the junction are easily accounted for in the iteration. A design example is included, and an experimental seventh-order filter designed and constructed using the procedure gives measured results that agree closely with theory     

Extraction and separation of molybdenum(VI) from acidic media by fatty hydrazides

BACKGROUND: The increasing demand for molybdenum has encouraged the development of low‐cost and environmentally friendly extractants to recycle and recover this metal. In the present study, solvent extraction of Mo(VI) from acidic media using a mixture of fatty hydrazides synthesised from palm olein as the extractant was carried out. The effects of various parameters such as acid, diluent, contact time, extractant concentration, metal ion concentration and stripping agent and the separation of Mo(VI) from other metal ions such as Co(II), Ni(II), Al(III) and Mn(II) were investigated. RESULTS: It was found that the extraction of Mo(VI) into the organic phase involved the formation of 1:3 complexes. Mo(VI) was successfully separated from commonly associated metal ions such as Ni(II), Co(II), Al(III) and Mn(II). Mo(VI) stripping from the loaded organic phase was studied using different acidic and alkaline solutions and was found to be optimal with ammonium hydroxide solution. CONCLUSION: These results are useful for the development of a method to recover Mo(VI) from acidic media utilising fatty hydrazides as the extractant. Copyright © 2008 Society of Chemical Industry     

Evanescent-mode coupling of dual-mode rectangular waveguide filters

A novel coupling method for dual-mode rectangular waveguide filters is presented and analyzed. Unequal coupling between dual-mode pairs of rectangular cavities is achieved without the need of an iris. This method replaces the iris completely while offering a practical, flexible, and wide range of couplings. The mode matching method is used in the analysis and its accuracy is verified by experiments. A four-pole dual-mode elliptic function filter using this new coupling method was built and tested. Results show excellent agreement with the analysis     

Dielectric ring resonators loaded in waveguide and on substrate

A rigorous mode matching technique is used to analyze the dielectric ring resonators loaded in a waveguide and on top of a substrate. Variation of several lowest order modes' resonant frequencies as a function of structure parameters is presented and is shown to be helpful for optimization of spurious mode separation. Two-dimensional electric and magnetic field line patterns and three-dimensional field intensity distributions of the ring resonators are plotted and provide information for mode excitation, coupling, and spurious mode suppression. Coupling between two dielectric ring resonators loaded in a metallic cavity are analyzed. The dielectric ring resonators are used to design a C-band elliptic function dual mode bandpass filter employing HE₁₁ modes. Experimental results are presented and show excellent agreement with the analytical solutions     

CNN: A speaker recognition system using a cascaded neural network

This work includes the design and implementation of both conventional, and neural network approaches to recognition of the speakers templates which are introduced to the system via a voice master card and preprocessed before extracting the features used in the recognltion. The conclusion is that the system performance in case of neural network is better than that of the conventional one, achieving a smooth degradation when dealing with nolsy patterns and higher performance when dealing with noise-free patterns.     

Identification of the Volatile Constituents of the Egyptian Lemongrass Oil. Part II. Thin Layer Chromatography

The chemical components of the Egyptian Lemongrass oil were analysed. The oil gained by steam distillation of the vegetative organs of the plant. Thin-layer chromatography of Lemongrass oil was tried with two solvent systems, i. e. cyclohexane: ethylacetate with 85:15, and hexane: ethylacetate with 90:10 V/V. The following results were obtained: The constituents of this oil were eight components. The oil sample proved that the citral component was detected in Egyptian Lemongrass oil with 0.64 R_f value. The oil obtained also geraniol, linalool and their esters. The nerol, cineal and citronellal were also detected.     

Query costs in HB(1) trees versus 2–3 trees

Query costs in random AVL trees are compared to those in random 2–3 trees. Both data structures are assumed to reside in main storage. Costs are calculated in terms of the number of node visits and key comparisons required to find a match or no match for a given key. The comparison is based upon theoretical concepts and implementation dependent considerations; e.g., data and instruction fetch. It is shown that if the cost of a key comparison is greater than or equal to the cost of a node access, then AVL trees are more advantageous.